/*
 * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Unlicense OR CC0-1.0
 */

#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <sys/stat.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_err.h"
#include "esp_log.h"
#include "usb/usb_host.h"
#include "msc_host.h"
#include "msc_host_vfs.h"
#include "ffconf.h"
#include "errno.h"
#include "driver/gpio.h"
#include "esp_vfs_fat.h"

#define USB_DISCONNECT_PIN  GPIO_NUM_10

#define READY_TO_UNINSTALL (HOST_NO_CLIENT | HOST_ALL_FREE)

typedef enum {
    HOST_NO_CLIENT = 0x1,
    HOST_ALL_FREE = 0x2,
    DEVICE_CONNECTED = 0x4,
    DEVICE_DISCONNECTED = 0x8,
    DEVICE_ADDRESS_MASK = 0xFF0,
} app_event_t;

static const char *TAG = "example";
static EventGroupHandle_t usb_flags;

static void msc_event_cb(const msc_host_event_t *event, void *arg)
{
    if (event->event == MSC_DEVICE_CONNECTED) {
        ESP_LOGI(TAG, "MSC device connected");
        // Obtained USB device address is placed after application events
        xEventGroupSetBits(usb_flags, DEVICE_CONNECTED | (event->device.address << 4));
    } else if (event->event == MSC_DEVICE_DISCONNECTED) {
        xEventGroupSetBits(usb_flags, DEVICE_DISCONNECTED);
        ESP_LOGI(TAG, "MSC device disconnected");
    }
}

static void print_device_info(msc_host_device_info_t *info)
{
    const size_t megabyte = 1024 * 1024;
    uint64_t capacity = ((uint64_t)info->sector_size * info->sector_count) / megabyte;

    printf("Device info:\n");
    printf("\t Capacity: %llu MB\n", capacity);
    printf("\t Sector size: %"PRIu32"\n", info->sector_size);
    printf("\t Sector count: %"PRIu32"\n", info->sector_count);
    printf("\t PID: 0x%4X \n", info->idProduct);
    printf("\t VID: 0x%4X \n", info->idVendor);
    wprintf(L"\t iProduct: %S \n", info->iProduct);
    wprintf(L"\t iManufacturer: %S \n", info->iManufacturer);
    wprintf(L"\t iSerialNumber: %S \n", info->iSerialNumber);
}

static bool file_exists(const char *file_path)
{
    struct stat buffer;
    return stat(file_path, &buffer) == 0;
}

static void file_operations(void)
{
    const char *directory = "/usb/esp";
    const char *file_path = "/usb/esp/test.txt";

    struct stat s = {0};
    bool directory_exists = stat(directory, &s) == 0;
    if (!directory_exists) {
        if (mkdir(directory, 0775) != 0) {
            ESP_LOGE(TAG, "mkdir failed with errno: %s", strerror(errno));
        }
    }

    if (!file_exists(file_path)) {
        ESP_LOGI(TAG, "Creating file");
        FILE *f = fopen(file_path, "w");
        if (f == NULL) {
            ESP_LOGE(TAG, "Failed to open file for writing");
            return;
        }
        fprintf(f, "Hello World!\n");
        fclose(f);
    }

    FILE *f;
    ESP_LOGI(TAG, "Reading file");
    f = fopen(file_path, "r");
    if (f == NULL) {
        ESP_LOGE(TAG, "Failed to open file for reading");
        return;
    }
    char line[64];
    fgets(line, sizeof(line), f);
    fclose(f);
    // strip newline
    char *pos = strchr(line, '\n');
    if (pos) {
        *pos = '\0';
    }
    ESP_LOGI(TAG, "Read from file: '%s'", line);
}

// Handles common USB host library events
static void handle_usb_events(void *args)
{
    while (1) {
        uint32_t event_flags;
        usb_host_lib_handle_events(portMAX_DELAY, &event_flags);

        // Release devices once all clients has deregistered
        if (event_flags & USB_HOST_LIB_EVENT_FLAGS_NO_CLIENTS) {
            usb_host_device_free_all();
            xEventGroupSetBits(usb_flags, HOST_NO_CLIENT);
        }
        // Give ready_to_uninstall_usb semaphore to indicate that USB Host library
        // can be deinitialized, and terminate this task.
        if (event_flags & USB_HOST_LIB_EVENT_FLAGS_ALL_FREE) {
            xEventGroupSetBits(usb_flags, HOST_ALL_FREE);
        }
    }

    vTaskDelete(NULL);
}

static uint8_t wait_for_msc_device(void)
{
    EventBits_t event;

    ESP_LOGI(TAG, "Waiting for USB stick to be connected");
    event = xEventGroupWaitBits(usb_flags, DEVICE_CONNECTED | DEVICE_ADDRESS_MASK,
                                pdTRUE, pdFALSE, portMAX_DELAY);
    ESP_LOGI(TAG, "connection...");
    // Extract USB device address from event group bits
    return (event & DEVICE_ADDRESS_MASK) >> 4;
}

static bool wait_for_event(EventBits_t event, TickType_t timeout)
{
    return xEventGroupWaitBits(usb_flags, event, pdTRUE, pdTRUE, timeout) & event;
}

void app_main(void)
{
    msc_host_device_handle_t msc_device;
    msc_host_vfs_handle_t vfs_handle;
    msc_host_device_info_t info;
    BaseType_t task_created;

    const gpio_config_t input_pin = {
        .pin_bit_mask = BIT64(USB_DISCONNECT_PIN),
        .mode = GPIO_MODE_INPUT,
        .pull_up_en = GPIO_PULLUP_ENABLE,
    };
    ESP_ERROR_CHECK(gpio_config(&input_pin));

    usb_flags = xEventGroupCreate();
    assert(usb_flags);

    const usb_host_config_t host_config = { .intr_flags = ESP_INTR_FLAG_LEVEL1 };
    ESP_ERROR_CHECK(usb_host_install(&host_config));
    task_created = xTaskCreate(handle_usb_events, "usb_events", 2048, NULL, 2, NULL);
    assert(task_created);

    const msc_host_driver_config_t msc_config = {
        .create_backround_task = true,
        .task_priority = 5,
        .stack_size = 4096,
        .callback = msc_event_cb,
    };
    ESP_ERROR_CHECK(msc_host_install(&msc_config));

    const esp_vfs_fat_mount_config_t mount_config = {
        .format_if_mount_failed = false,
        .max_files = 3,
        .allocation_unit_size = 1024,
    };

    do {
        uint8_t device_address = wait_for_msc_device();

        ESP_ERROR_CHECK(msc_host_install_device(device_address, &msc_device));

        msc_host_print_descriptors(msc_device);

        ESP_ERROR_CHECK(msc_host_get_device_info(msc_device, &info));
        print_device_info(&info);

        ESP_ERROR_CHECK(msc_host_vfs_register(msc_device, "/usb", &mount_config, &vfs_handle));

        while (!wait_for_event(DEVICE_DISCONNECTED, 200)) {
            file_operations();
        }

        xEventGroupClearBits(usb_flags, READY_TO_UNINSTALL);
        ESP_ERROR_CHECK(msc_host_vfs_unregister(vfs_handle));
        ESP_ERROR_CHECK(msc_host_uninstall_device(msc_device));

    } while (gpio_get_level(USB_DISCONNECT_PIN) != 0);

    ESP_LOGI(TAG, "Uninitializing USB ...");
    ESP_ERROR_CHECK(msc_host_uninstall());
    wait_for_event(READY_TO_UNINSTALL, portMAX_DELAY);
    ESP_ERROR_CHECK(usb_host_uninstall());
    ESP_LOGI(TAG, "Done");
}